1. Field of the Invention
The present invention relates to a frame of a reciprocating compressor, and more particularly, to a frame of a reciprocating compressor composed of two components and having an oil flow path provided therein when the two frame components are assembled.
2. Description of the Background Art
Generally, a compressor is an apparatus for compressing a refrigerant gas under the condition of low temperature and pressure, which is introduced from an evaporator, and discharging the gas by changing the condition to high temperature and pressure.
Compressors can be classified as rotary compressors, reciprocating compressors and scroll compressors according to the method of compressing the fluid.
Particularly, the reciprocating compressor takes in by suction and compresses the fluid while a piston moves linearly. The operational method of the reciprocating compressor is divided into a method which compresses fluid by converting the rotary movement of a driving motor into a reciprocating movement of the piston, and a method which takes in a fluid by suction and compresses the fluid by having the piston perform a reciprocating movement as the driving motor performs a linear reciprocating movement.
FIG. 1 is a longitudinal sectional view showing a conventional reciprocating compressor, FIG. 2 is a perspective view showing a frame of the conventional reciprocating compressor, and FIG. 3 is an enlarged sectional view of a portion of FIG. 1.
As shown in FIG. 1, the conventional reciprocating compressor includes a case 10 having a gas suction pipe SP, gas discharge pipe DP, and a supporting member 20 installed inside the case 10. A reciprocating motor 30 is fixed to the supporting member 20 for reciprocating a movable element 33, a compression unit 40 for taking-in, compressing and discharging gas by the movable element 33 of the reciprocating motor 30 are provided. A resonance spring unit 50 elastically supports the movable element 33 of the reciprocating motor 30 in the movement direction, and a supply unit 60, mounted at the supporting member 20, supplies oil to the compression unit 40.
The supporting member 20 comprises a frame 21 for supporting the reciprocating motor 30 and the compression unit 40, a middle cover 22 for supporting an outer stator 31 of the reciprocating motor 30, and a back cover 23 for supporting the resonance spring unit 50.
A boss 21B having an insertion hole 21a is formed at the center portion of the frame 21 and a flange 21A is formed at the outer circumference thereof (FIG. 2).
A cylinder 41 which will be explained later is inserted into the insertion hole 21a, and an inner stator 32 is installed at the outer circumference of the flange 21A.
The reciprocating motor 30 comprises an outer stator 31 installed between the frame 21 and the middle cover 22, an inner stator 32 which is spaced from the outer stator 31 by a predetermined interval and fixed to the frame 21, a movable element 33 installed between the outer stator 31 and the inner stator 32 for performing a linear reciprocating movement, and a coil 34 to which electric current flows.
The compression unit 40 comprises: a cylinder 41 integrally formed in the frame 21, a piston 42 engaged to the movable element 33 of the reciprocating motor 30 for performing a reciprocating movement in a compression space P of the cylinder 41, a suction valve 43 mounted at the front end of the piston 42 for controlling suction of refrigerant gas by opening and closing a suction path F (FIG. 3) of the piston 42 and a discharging valve assembly 44 mounted at a discharge side of the cylinder 41 for controlling discharge of compression gas by opening and closing the compression space P.
The oil supply unit 60 comprises an oil pumping portion 61 for pumping oil in the case 10, and an oil supply path 62 formed at the supporting member 20 to connect an outlet of the oil pumping portion 61 and the compression unit 40.
As shown in FIG. 3, the oil supply unit 62 comprises a suction hole 62a extending from the frame 21 to an inner circumference surface of the cylinder 41, a first oil pocket 62b formed at the inner circumference surface of the boss 21B of the frame 21 by being connected to the oil suction hole 62a, an oil opening 62c formed to penetrate the cylinder 41 for connecting the first oil pocket 62b to the outer circumference surface of the piston 42 and a second oil pocket 62d in contact with the oil opening 62c and formed concavely with a ring shape at the outer circumference surface of the piston 42. An oil discharge hole 62e is formed to extend from the upper front side of the first oil pocket 62b to the outer side of the flange 21A and an oil recollecting path 62f in contact with the oil discharge hole 62a for recollecting oil.
The conventional reciprocating compressor operates as follows.
When a flux is formed between the outer stator 31 and the inner stator 32 by applying current from a power source to the reciprocating motor 30, the movable element 33 elastically performs a reciprocating movement by the resonance spring unit 50. At this time, as the piston 42 performs a reciprocating movement inside the cylinder 41, the volume of the compression space P is changed, and the gas is taken-in, compressed, and discharged, which processes are sequentially repeated.
At the same time, the oil pumping portion 61 pumps oil in the case 10. The oil passes through an oil discharge valve to pass into the oil suction hole 62a, the first oil pocket 62b, and the oil opening 62c and flows into the second oil pocket 62d, thereby cooling parts near the compression unit and provides lubrication between the piston 42 and the cylinder 41.
Then, oil of the second oil pocket 62d is recollected by returning to the case 10 through the oil discharge hole 62c and along the oil recollecting path 62f. 
In the conventional reciprocating compressor, the frame 21 in which the flange 21A and the boss 21B are provided, is formed as a unitary member (FIG. 2).
However, in the conventional reciprocating compressor, the frame has to be formed as a three dimensional shape in order to receive the outer stator of the motor, the inner stator, the cylinder, and the discharging valve assembly therein. Accordingly, many sophisticated manufacturing processes are required, the fabricating process becomes difficult, the fabricating cost is increased, and a reliability of the compressor is degraded when wrong processing is performed.
Also, in case of expanding an area of the oil path so as to increase the oil inflow amount for effective lubrication and cooling of the compression unit, it is difficult to process (i.e., fabricate) the oil supply path. Accordingly, there is a restriction in properly controlling the inflow amount of the oil.